The present invention relates generally to improvements in breast pumps and more particularly pertains to a combination of an electric pump with improved controls and a flexible breast cup which simulate the action of a nursing infant.
Although the prior art breast pumps and, specifically, the prior art breast pump described and claimed in U.S. Pat. No. 6,383,163 are effective, they also have a number of shortcomings. For example, most prior art breast pumps and breast cup systems only allow a mother to express her milk by applying a uniform vacuum pressure (or vacuum pressure profile) to the face of the breast. This simple approach does not effectively mimic the natural suckling of a nursing infant. As a result, the pump and breast cup system does not extract the milk as efficiently as possible. Consequently, a longer pumping period is required, which increases the physical demands on the mother. These demands may discourage working mothers, or mothers still recovering from childbirth, from thoroughly completing the expression. Incomplete or improper expression of the milk may lead to engorgement of the breasts, mastitis, or infection.
Although the prior art breast pumps and, specifically, the prior art breast pump described and claimed in U.S. Pat. No. 6,383,163 are very effective, these prior art pumps do not contemplate controlling the refractory time of the suction cycle. The result is that the pump is not as efficient as it could be in removing the breast milk. As a result of this decreased efficiency, a longer overall pumping period is required. The longer period increases the physical demands on the user. Moreover, most prior art breast pumps only apply a suction face to the breast for expressing the mother's milk.
In a natural suckling cycle, refractory time of the breast plays an important role in optimizing the efficiency of milk extraction. The refractory time is that part of the nursing cycle that begins after milk has been drawn from ducts within the breast, and ends when the depleted portions of the milk ducts refill. One invention that accounts for this refractory time is disclosed in U.S. patent application Ser. No. 10/644,199, assigned to the assignee of the present invention. The '199 application discloses a breast pump which draws a vacuum in periodic pulses at a frequency that may be adjusted by the mother to track her physiological refractory time.
Nursing an infant, however, is a biological process that is not so easily modeled with mathematical precision. Many conditions can change during expression of the milk. Perhaps the most obvious example is the onset of the let-down, or milk-ejection reflex. Research has shown that prior to let-down, an infant will suck at an elevated rate in the range of 72 to 120 sucks per minute. After let-down, when a satisfactory flow of milk is obtained, the infant relaxes the rate down to around 60 sucks per minute. The vacuum drawn by a suckling infant may vary between 18 mmHg and 200 mmHg. After let-down, an infant typically applies a greater suction force than before let-down. In addition, as the store of milk in the alveoli diminishes, the infant may apply a higher suction force to sustain the flow.
The optimal refractory times, vacuum pressures, and vacuum pressure profiles will vary among different mothers. What is needed, then, is a breast pump that can be easily customized to optimize the efficiency of expression over a wide range of conditions.